Targeted Lymphoma Cell Death by Novel Signal Transduction Modifications
Annual rept. 15 Jun 2007-14 Jun 2008
CALIFORNIA UNIV DAVIS DAVIS MEDICAL CENTER
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The proposed research set to 1create and characterize CD22-binding peptides that initiate signal transduction and apoptosis in NHL., 2 optimize CD22- mediated signal transduction and lymphomacidal properties of ligand blocking anti-CD22 mAbs and peptides with CD22-specific phosphatase inhibition and 3 correlate mAb-mediatedand anti-CD22 peptide-mediated in vivo physiologic changes, efficacy, and tumor targeting using advanced iPET and FDG-PET imaging technology. Since funding we have identified five peptides that are based on CDRs of anti-CD22 mAbs. Only the sequence derived from heavy chain CDR2 Peptide 5 demonstrated significant B-cell binding. Peptide5 bound to both malignant and primary B-cells with very little T-cell binding. The affinity had a Km of 5x10-6M. Peptide 5 mediated killing of several NHL cell lines to a degree similar to that of the parent mAb HB22.7. Peptide 5s loop structure was shown to be crucial for B-cell binding and ligand blocking. Mutational analysis revealed that most amino acids were critical for B cell binding. Using a CD22 transfected COS cell line, we demonstrated CD22-specific binding and CD22 ligand blocking to a degree similar to HB22.7. Finally Peptide 5 was used as a vehicle to deliver a pro-apoptotic peptide into NHL cells. Peptide 5 was fused to a BH3 death domain-containing peptide which demonstrated more effective NHL cell killing than the parent peptide.
- Medicine and Medical Research